Rock drill



L. W. GREVE i ROCK DRILL Feb. 21, 1933.

Filed Aug. 21, 1928 IN VEN TOR.

ATTORNEY Patented Feb. 2l, 1933 UNITED STATES COMPANY, on CLEVELAND,onto ROCK DRILL Application filed August 21, 1928. \Seria1-1\m.30lj,055.

The present invention is directed to improvements in rock drills, andhas for its primary object to provide a drill constructed in such mannerthat the motive fluid flow- 5 ingfrom the line will be subjected toheat,

to increase the expansibility of the compressed air before it is allowedto expand.

A further object of the invention is to provide a device of this kindwhich will be particularly desirable at locations where air pressure iscomparatively low, and will prove especially advantageous when used inconnection with portable compressors of the type used for operatingtools for street and road work. l

lVith these and other objects in View, as will appear as the descriptionproceeds, the invention consists in the novel features of construction,combination of elements, and

arrangement of parts hereinafter to be fully described, and particularlypointed out in the appended claims.

In the accompanying drawing Figure l is a sectional View taken through'the device.

Figure 2 is a sectional view o-n line 2-2 of Figure l.

Referring to the drawing, 1 designates the drill cylinder in which ismovable the piston hammer 2, said cylinder and hammer being of anyconventional type.

The back head 3 is formed with a relatively large air receiving chamber4, motive fluid being led thereto throughV a port 5,

the inflow of fluid being controlled by a valve 6, operable in thisinstance, by a trigger 7 carried by the handle structure 8. The chamberis preferably provided with a lining 9 of suitable material having lowheat conducting qualities. A lining of refractory material such asasbestos or ire brick will suflice for this purpose.

The heating unit. per se consists of a cylinder l0 formed from moistureresisting material, for example, stainless steel, as well as havinggreat heat conductivity. Fitting snugly upon the cylinder is a sleeve 1lof suitable insulating material for example, porcelain, and in which isformed a plurality of perforations l2. This sleeve is of the LOUIS w.GREVE, or CLEVELAND, OHIO, AssrGNon 'refrain cLnvnpeNnnocizfnnirL Samelillllgtll as the Cylinder l, v.affidiZlib-,0111i i i have ytheir lower,ends resting Lupon, the spacing lmember 13 which serves. to ,maintainthe same zfirmlymin the-chamberA, ,and spaced fnoinfgthe sidev-Wall'tliereof. .The outersur'- face of the SleeveiS-fgrooved, as.-atleiolt retaining the lwire 15 properly wound, V1 -he terminals 16`andy lltbereof being connected in ,the receptacle H1,8, said receptaclebeing of conventional form 3and is lunounted inthe/re? lcess l9fformedinthe .wall of the chamber.

This receptacle :is y.retained :in ,placefbyfthe plate 20andit .will ,beobviouslthat `when la plug, connected in circuitwitha lsourcebfelectrical energy isengaged in the receptacle, theswire l5 .will vaberheated. .Qbviouslvthe heat from the wire l5 will radiate throughtheperiforations .off-thefsleeve, thus heating thecylinder 10 in orderthat the motive fluid passing through the cylinder will be heatedthereby increasing the potential expansive power of the motive fluidjust prior to the time it enters the piston chamber to act upon thepiston and thus greatly increasing the efliciency thereof.

What is claimed is l. In combination with a drill cylinder having ahammer piston reciprocatively mounted therein, a back head, a heatingchamber disposed within said` back head having heat insulating walls, aheating unit disposed within said heating chamber, said unit beingcoextensive with said chamber and having walls parallel and spaced fromsaid chamber walls, a spacer disposed between said back head and saiddrill cylinder, said spacer adapted to maintain said heating unit inposition within said heating chamber with its ends in engagement withsaid back head and said spacer, and means for conducting motive fluidfrom a source of supply through said heating chamber and unit to' saiddrill cylinder.

2.y In combination with a drill cylinder having a hammer pistonreciprocatively mounted therein, a back head, a spacer member disposedbetween said drill cylinder and said back head, an enlarged chamberWit-hin said back head having a lining of heatinsulating material, acylinder of high heat conducting material, disposed Within said chamberand in abutting relation with said spacer member and back head, a sleeveof electrical insulating material disposed about said cylinder', heatingcoils supported by said cylinder, and means Jfor conducting motive fluidfrom a source of supply through said heating chamber andA cylinder tosaid drill cylinder. g. E* ,Y 1o 3Q In rcombination With a drillcylinder having a hammer piston reciprocatively mounted thereinya backhead, a spacer member disposed between said drill cylinder and said backhead, an enlarged heating chamber within said back head having a liningof heat insulating material, a heating unit disposed Within saidchamber, said heating unit being in the form of a metal cylinder havingwalls of relatively high heat conductivity7 ay porous electricalinsulating member surrounding said metal cylinder, a resistance coilWound onfsaid porous member; said unit being spaced from the Walls ofsaid heating chamber and having its ends abutting said back head andsaid spacer' member and being held in position by saidback head andmember, and means for conducting motive fluid from a source of fluidsupply through said heating chamber and unit to said drill cylinder. YIn testimony whereof I affix my signature. Y

' LOUIS GREVE.

